How do you pass an object through a function using a pointer?

I wanted to pass an object - which is also a vector - through a function using pointers.

I believe the issue arises on line 75 (transaction(&user, userID);) where I attempt to pass the object "user" through to the function "transaction".
I don't believe the classes are relevant so I left them out. Thank you so much in advance. Here is the source.cpp code: